1. Field of the Invention
The present invention relates to an image forming apparatus for forming an image on a sheet. More specifically, the present invention relates to an image forming apparatus provided with an endless transfer member.
2. Description of the Related Art
Conventional image forming apparatus are known to be provided with an endless transfer member such as an endless type transfer belt, cylindrical transfer drum or the like. A sheet is supported on an exterior surface of the transfer member. Said transfer member is rotated a number of rotations corresponding to the number of colors being transferred. A multi-color image is formed by overlaying on said sheet a toner of a different color on each single rotation. Methods for supporting a sheet on the aforesaid endless transfer member include charging the surface of the endless transfer member, so as to support a sheet on the surface of said endless transfer member via the force of electrostatic attraction.
However, such methods are disadvantageous inasmuch as suitably supporting a sheet on the transfer member cannot be accomplished when a stiff sheet, such as a thick paper sheet, overhead projector transparency (hereinafter referred to as "OHP sheet"), or the like, is supported on the aforesaid endless transfer member having a large curvature, inasmuch as the leading edge of the sheet separates from the surface of the endless transfer member and curls upward.
If a large diameter (i.e., small curvature) endless transfer member is used, stiff sheets can be suitably supported on the surface thereof. However, a large space is required to accommodate the installation of such an endless transfer member, thereby increasing the overall size of the apparatus itself.